this is a deeper subject to we are into. this is how we would perform basically with different levels. and we look deaths of more intense storms. so our existing systems, 1.3 inches, this map shows where the flooding would occur, and the darker areas are more intense flooding. this is up by the creek, lower mission creek. then, let's look at these storms. this is something that i think has to be pointed out. within that three-hour duration,

there is a variety of intensity. there are a number of different speeds over that little journey, but in this three-hour period, there is a piece that will occur, and the intensities are measured. so if we look at that same system, with a little bit more intensity, the flooding is much wider spread and much more severe, the severe be in the dark blue -- being the dark blue. so what we did was take a look at the areas that are susceptible to flooding, and this is based on the modeling work. some of them are here today who have done this modeling. they go out, and they have a program. they go out there in their rain your -- gear.

unfortunately, across the city, it does not remain the same in any given location. in one area, you may not get any rain. then we took a look at upgrades. these are included note in the program. what type of flooding would we then see? you can see this would be diminished for the same level of storm. with all of the different flood control projects, the only place we're really seeing an issue is the creek. but it looks quite good over the rest of the city. >> vs. solly? >> what we did is we used a

percentage -- versus? >> what we did is we used a percentage. i think he could probably give you a quick overview. >> david. there is an assumption that the city is already moving forward with a certain amount of green infrastructure, so that was considered a baseline that we put into the model, and then beyond that, we had specific combinations in projects around the city to solve the problems. our goal was to not focus in on note any individual project or combination of projects but to look about a similar cost. they decided to tweak it slightly differently.

in terms of what was gray and what was korean, -- green, they were being evaluated, and we used those as a starting point. >> we have the connection, which included structures, and then we had an allowance of approximately 30% of the streets within san francisco, and we spread that out over a period of time. the investment started out at $8 million a year and went up. all of this was spread evenly.

there are areas where we still see flooding challenges. we still see it the same problems coming back. of the areas we should do being susceptible to flooding, these are the highlighted areas, so we took a lot of kosc -- took a look at the costs. so what if we look at a higher cost?

actually doubling. it is going to take gray and green, but perhaps you want to spend a minute on this particular side. this is our design. we are challenged in certain areas.

i will talk to you about what we've looked at so far, and i can proceed in that. >> this will go with the 1.3 inches over three hours. trying to get a fairly small incremental difference. i wanted to make sure that we are not glossing over that. >> we really tried to address

this. this looked at things at a higher level. >> i would just make a comment. if we buy one level of protection today, it will be less protection tomorrow. >> i think everybody is agreeing that we believe that there will be more intense storms. the issue is it can have couple pitkin -- a couple to go. we can handle that.

>> when you say handled, what exactly do you mean? is it just going down the sewer? >> now we realize the basis. we see issues where we are having manholes coming up, or there is property damage, but the street has been designed to contain that water. that is part of the design, and what we want to avoid is having in areas where we are always having challenges, and the surrounding area -- we do not want to have that. but --

>> you are saying it is open? is that you are saying? >> some of the areas are to be challenged where the collection system in diameter or size may be half as big as it needs to be. now, we will look at putting in a bigger pipes it, green infrastructure. some areas are just underserved with what we have got. >> some areas historically workweeks and lakes, so it is not necessarily underserved, but it is a different kind of issue. >> or the cayuga issue we have talked about.

this causes a problem. >> seeing those more intense storms. >> we look back over our historical data, and we have not seen a change yet in intensity or duration. it looks like it was trekking on note a basis. putting things in different areas. the focus has been consolidation, but our team did

look at if we had seen any changes, and that is a check will have to do. >> the climate change models are not really finite. much more global. we can take a look at it particularly as relates to the outflows. getting money in congress to build a model of. >> i do not understand what type of investment. i wanted to talk a little bit about what we did would korean

alternatives. -- green alternatives. we took a look at the management. this map shows the two areas. internally, this is the cayuga area wrote bad experiences flooding.

downspout disconnection and storm water capture, where reconstructed physical reservoir at a lower elevation so we can capture stormwater before it gets into the system. this is the old reservoir, what that could look like if we use that as a storage basin, so there that is. the rainwater gets in there, and they can play soccer or have a recreational area, but the storm water could be used for beneficial uses.

so these green improvements within each watershed, we would have additional sources of water that we could use as another form of water re-use. other systems have shown greater improvement of the water quality. it would provide community enhancement, the greening. it slows the water down and gives it another way to go. it is another pathway. a tunnel or infrastructure, eso the types of projects that we will be looking at to solve the problem to me to the level of

service, it would be increased collection capacity, the daylighting, the undrawn -- the underground systems. and we need to get some more experience under our belt. we're looking at focused watershed planning efforts and coming back to the commission in the fall to be able to say this is a watershed we would like to be able to start with and really looking at the watershed, et what creeks are there, the to be terry danish -- the tributary dane drink -- drainage. it has to be put through a triple bottom line analysis so we get a long-term kerf -- kerf -- curve.

we want to make sure that captured water can be reused, and strategically, will be focusing on. that are susceptible to flooding, that i showed you in an earlier slide. i reviewed them earlier. we would be dealing with new technology. we have to develop guidance for

the rest of the city. to be an effective part of the system, we have a lot still to learn, and a channel tunnel would be one that we would be looking to start right away, and that is a major asset, and we are looking at what we can do on the surface to manage storm water and will begin to below the service to know the we have reliability. >> ongoing maintenance for a better street.

>> dpw in general is responsible for street maintenance. it is a cross departmental kind of effort. it sounds like an issue. >> it sounds like an issue. they have not been fully defined. >> performance has to be monitored. when there is a replacement of any infrastructure below it, the right pavement has to be put in.

caring for it. it is complex. it is a new area of business for us. >> we really need to figure out what elements are sustainable. and with normal human behavior, what might not be sustainable over time. >> we would like to be able to press forward the with this goal and this level of service. commissioner moran: i am not comfortable with this.

this all makes sense to me over time. i do have some concern about a level, given that we believe the severity of storms is going to increase overtime. tell me if i am wrong. the cost curve does not apply to every element of a program. what i mean by that is in the case you're putting a pipe in the ground, in an incremental

cost on that may not be huge. you are trying to upgrade and optimize the size, i am wondering if that is the sensible thing to do. if we have opportunities to build more capacity, and the incremental cost is not there, then why would we not do that? especially if it is a hedge, having to tear up the streets and to the wholesome and over again. -- and to the polls and over again. >> we will be limited -- and do the whole thing over again. >> we will be limited. we will have to upsize the

plant. we will probably be replacing things. and that is why you see this escalation it would mean that we are collecting and spending a lot more water to the treatment plants beyond their capacity. we are trying to manage the water this is why you see that deep slope on that curve.

commissioner moran: this seems unreasonable. >> this is such a big one. a lot of defects are known. there is cause and effect with everything. -- a lot note -- of effects are known. we have to manage them in a different way. right now, that is what happens. they are holding these above- ground in challenging the residents and causing problems.

commissioner moran: how can we best protect ourselves? how do we protect ourselves against that? >> what we're trying to do to be able to avoid that is, and this

is difficult. we're trying to look at each of the basins and their characteristics, what infrastructure is there, what are the challenges. what is the problem now. is it a collection system proof is in a creek that is causing a problem? what is the nature of the problem, and then we are looking to identify solutions, and say, this neighborhood is going to be further challenged if we of climate change and look at different levels of intensity, but our plan to manage this is

looking at a more intense basis and look at all of the tools in our toolbox, gray, green, everything. one solution. commissioner: we have had this discussion, so why is a 1.3, and what if we did 1.5 q or there, and the response that i was getting is that the whole system is designed for 1.3. going in and putting in small portions of your upgrading to a, a different size storm does not do any good because the rest is not accommodating. in some cases, it would probably cause trouble because there was a larger capacity and i think it

may be in some ways, not to get somebody crazy, but building a new bicycle lane on the bay bridge. it russia off on treasure island, and you cannot get here. it may be a good idea long term note, but until then, -- is inappropriate to start sending money? i think that is part of the trade-off. commissioner moran: if you're planning for uncertainty, maybe you would plan for that.

>> it is designed for 1.3. commission moran: if you design it for 1.3, and then you have a year of 1.5 or 1.6, we do year of 1.5 or 1.6, we do >> it would be a lot to do that.